This invention relates to a monochromator used in a spectrophotometer or the like.
A monochromator is available in the form of a single monochromator adapted to dispose one dispersion element in an optical path, and a double monochromator adapted to arrange two dispersion elements in series with each other in the optical path. the single monochromator is simple in its structure but involves much stray light whereas the double monochromator is subject to much less stray light but has a lower sensitivity, viz., lower luminous intensity. In view of the fact that these monochromators have both merits and demerits, proper use of one type of monochromator or the other depends on the object to be measured.
Both single and double monochromators which are designed so that the diffraction gratings as dispersion elements are selected and switched over interchangeably in usage have been well known.
In both cases, however, one diffraction grating is used in a single monochromator for switchover while one or both of the diffraction gratings which are provided in pairs are employed in a double monochromator. For this reason, the single monochromator has no other function, and the double monochromator likewise, so that they are only used in their own individual applications and nothing more.
Consequently, inconvenience results when various measurements need to be made, since both the single and the double monochromators need to be prepared beforehand.